The Department of Immunology and Infectious Diseases (DIID) in the Division of Biologic Sciences (DBS) at the Harvard School of Public Health (HSPH) comprises a strong team of accomplished scientists who work on problems related to the immune response and to the biology, epidemiology and immunology of infectious diseases. DBS, established in 1993, is an umbrella structure that encompasses the biologic laboratory sciences in the areas of Immunology and Infectious Diseases, Cancer Cell Biology, Environmental Health, and Nutrition. The Ph.D. Program in Biological Sciences in Public Health (BPH) is located at HSPH and is offered by the Graduate School of Arts and Sciences. This pre-doctoral training grant competitive renewal application would support BPH students who choose to work in laboratories of faculty members of the Department of Immunology and Infectious Diseases. The BPH program provides a unique opportunity for training a cadre of leaders who possess expertise in the individual fields of biological research and a broad interdisciplinary knowledge of epidemiology and biostatistics. It has become increasingly evident that progress in disease prevention is optimally promoted by a close interaction between epidemiologists and laboratory scientists, where laboratory discoveries and epidemiological observations interact in an iterative manner to advance research in both fields. Furthermore, basic biological and epidemiological discoveries must be placed in a wide social context. This program encourages active collaboration among scientists who share complementary interests in developing closer linkages between laboratory research and field work- all with an eye to developing innovative approaches to prevention. Our training record in this grant period has been excellent as evidenced by the publication record and career paths of the pre-doctoral students supported. The 18 Faculty members in DIID are: the Program Director, Dr. L. Glimcher, gene expression in lymphocytes with a focus on cytokines, autoimmunity;Dr. M. Grusby, T helper cell differentiation with a focus on cytokine signal transduction, allergy;Dr. I-C. Ho, cytokine gene transcription;Dr. B. Bloom, tuberculosis, vaccine development, T cell activation;Dr. I. Kramnik, tuberculosis, immune mechanisms of protection;Dr. E. Rubin, molecular genetics of tuberculosis;Dr. D. Harn, leishmaniasis, schistosomiasis, immunology, molecular biology;Dr. A. Spielman, medical entomology, Lyme disease, erlichiosis;Dr. D. Wirth, malaria, leishmaniasis, drug resistance, vaccine development;Dr. B. Burleigh, cell biology, T. cruzi, malaria;Dr. M. Duraisingh, malaria;Dr. M. Essex, Drs. T-H. Lee, P. Kanki, HIV, co-infection with parasites, vaccine development. In addition, 4 faculty members with primary appointments at the Harvard Medical School will participate: Dr. J. Lieberman, HIV;Dr. H. Ploegh, cell biology and Dr. J. Sodroski, HIV, and Dr. A. Tzianabos, bacterial infection.